feat: queries related to lsn updated

Signed-off-by: Emanuel Calvo <3manuek@gmail.com>

sql/Checkpoints/checkpoint_distance.sql

@@ -1,3 +1,2 @@
--- Given the current xlog location, it calculates the size of the current active WAL
--- Source: https://www.cybertec-postgresql.com/en/checkpoint-distance-and-amount-of-wal/
-SELECT pg_size_pretty(pg_current_xlog_location() - '0/00000000'::pg_lsn);
+-- Amount of generated WALS so far
+SELECT pg_size_pretty(pg_current_wal_lsn() - '0/00000000'::pg_lsn);

sql/Checkpoints/checkpoint_distance_v9.sql

@@ -0,0 +1,3 @@
+-- Given the current xlog location, it calculates the size of the current active WAL
+-- Source: https://www.cybertec-postgresql.com/en/checkpoint-distance-and-amount-of-wal/
+SELECT pg_size_pretty(pg_current_xlog_location() - '0/00000000'::pg_lsn);

sql/WAL/distance_wals_from_dir.sql

@@ -0,0 +1,12 @@
+-- Current amount of WALs present in the waldir
+WITH oldest_mod_walfile AS (
+    SELECT (substring(name from 9 for 8) || '/' || substring(name from 17 for 8 ))::pg_lsn as oldest_lsn
+        FROM pg_ls_waldir() 
+        ORDER BY modification DESC LIMIT 1
+)
+SELECT pg_size_pretty(pg_wal_lsn_diff( pg_current_wal_lsn(),oldest_lsn))
+FROM oldest_mod_walfile;
+
+
+
+